水合物羽状流数值模拟及地震响应特征研究

项目名称： 水合物羽状流数值模拟及地震响应特征研究

项目编号： No.41306050

项目类型： 青年科学基金项目

立项/批准年度： 2014

项目学科： 天文学、地球科学

项目作者： 李灿苹

作者单位： 广东海洋大学

项目金额： 27万元

中文摘要： 地层深部大量气体沿着断层或裂隙向上运移，泄露到海水中形成气泡羽状流，羽状流发育区常发现富含天然气水合物的海底沉积层，因此，羽状流可作为水合物存在的间接证据。目前，地震方法已能检测到羽状流，但对羽状流地震响应尚缺乏深入研究。由此，本项目拟开展羽状流数值模拟及地震响应特征研究，具体为：根据含气泡海水声波速度模型及随机介质理论或等效介质理论建立羽状流模型，包含气泡半径和含量两个模型参量；利用有限差分法求解声波方程进行正演模拟羽状流地震波场，分析总结羽状流产生的地震散射波场特征；应用地震散射成像理论对羽状流炮集地震数据进行叠前深度偏移成像处理；利用叠前和叠后地震资料提取对气泡半径和含量敏感的地震属性，建立模型参量与地震属性之间的关系，再由含羽状流的实际地震资料验证二者之间的关系。本研究为地震方法识别水合物羽状流提供理论参考依据，其成果有助于进一步探索水合物分解和运移规律及海水中甲烷气泡的分布规律。

中文关键词： 羽状流；水合物；等效介质；逆时偏移；属性分析

英文摘要： Plentiful gases in deeper sediments migrate upwards along faults or cracks and leak into the sea water, and produce a bubble plume. The seafloor sediments abundant with gas hydrates are commonly found in the plume occurrence areas. Therefore, the plume may be an indirect evidence of the gas hydrate existence. At present seismic methods can be used to identify plumes,whereas the seismic response of plumes still lacks deep research. Thereby, this project will carry out study on the seismic response characteristics and the numerical simulation of plumes. Main research contents in this program are as follows. The plume model is constructed based on the acoustic wave velocity model in the sea water containing bubbles and random medium theory or equivalent medium theory, and it includes model parameters of bubble radiuses and bubble contents. The equation of acoustic wave is solved by finite difference and the seismic wave field of plumes is forward simulated. The seismic scattered wave field characteristics produced by plumes are analyzed and summarized. Seismic data of shot gathers are processed by prestack depth migration imaging using seismic scattered wave imaging theory. Seismic attributes sensitive to bubble radiuses and bubble contents are extracted by prestack and poststack seismic data, the relationship betw

英文关键词： plume；hydrate；effective medium；reverse-time migration；attribute analysis